Welding is a process that has increasingly become ubiquitous in all industries. Welding is, at its core, simply a way of bonding two pieces of metal. A wide range of welding systems and welding control regimes have been implemented for various purposes. In continuous welding operations, metal inert gas (MIG) welding and submerged arc welding (SAW) techniques allow for formation of a continuing weld bead by feeding welding wire shielded by inert gas from a welding torch. Such wire feeding systems are available for other welding systems, such as tungsten inert gas (TIG) welding. Electrical power is applied to the welding wire and a circuit is completed through the workpiece to sustain a welding arc that melts the electrode wire and the workpiece to form the desired weld.
While very effective in many applications, these welding techniques may experience different initial welding performance based upon whether the weld is started with the electrode “cold” or “hot.” In general, a cold electrode start may be considered a start in which the electrode tip and adjacent metals are at or relatively near the ambient temperature. Hot electrode starts, by contrast, are typically those in which the electrode tip and adjacent metals are much more elevated, but below the melting point of the electrode wire. In some applications, it is believed that initiation of welding arcs and welds is facilitated when the electrode is hot. However, the current state of the art does not provide regimes designed to ensure that the electrode is heated prior to initiation of a welding operation.
Certain advancements have been made to the process of electrode preheating. For example, U.S. Patent Publication No. 2014/0021183 A1 to Peters describes a welding torch having a contact tip that has electrically isolated upper and lower portions, each portion providing part of the aggregated welding current waveform. Similarly, U.S. Pat. Nos. 4,447,703, 4,547,654, and 4,667,083, as well as PCT Publication No. WO/2005/030422, describe various preheating techniques using a dual contact tip. Despite the foregoing, a need remains for improved welding strategies that allow for welding initiation with a heated electrode wire so as to improve weld performance.